Materials for organic electroluminescent devices

Abstract

The invention relates to compounds which are suitable for use in electronic devices, and to electronic devices, in particular organic electroluminescent devices, containing said compounds.

Claims

1. A compound of formula (1) ##STR00310## where the symbols and indices used are as follows: A is O or S; X two adjacent X are a group of the formula (2) ##STR00311## where ^ indicates the corresponding adjacent X groups in formula (1), and the two remaining X groups are CR; Z is CR; or two adjacent Z are a group of the formula (2a) and the two other Z are CR, ##STR00312## formula (2a) where ^ indicates the corresponding adjacent Z groups in formula (2); W here is O, S, NR or CR.sub.2; Ar is an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted by one or more R radicals; R is the same or different at each instance and is selected from the group consisting of H, D, F, Cl, Br, I, CN, NO.sub.2, N(Ar.sup.1).sub.2, N(R.sup.1).sub.2, P(Ar.sup.1).sub.2, B(Ar.sup.1).sub.2, Si(Ar.sup.1).sub.3, Si(R.sup.1).sub.3, a straight-chain alkyl, alkoxy or thioalkyl group having 1 to 40 carbon atoms or a branched or cyclic alkyl, alkoxy or thioalkyl group having 3 to 40 carbon atoms or an alkenyl or alkynyl group having 2 to 40 carbon atoms, each of which may be substituted by one or more R.sup.1 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by R.sup.1CCR.sup.1, CC, Si(R.sup.1).sub.2, CS, CNR.sup.1, SO.sub.2, NR.sup.1, O, S or CONR.sup.1 and where one or more hydrogen atoms may be replaced by D, F, Cl, Br, I, CN or NO.sub.2, an aromatic ring system which has 5 to 60 aromatic ring atoms and may be substituted in each case by one or more R.sup.1 radicals, an aryloxy or heteroaryloxy group which has 5 to 40 aromatic ring atoms and may be substituted by one or more R.sup.1 radicals; at the same time, it is optionally possible for two adjacent R substituents to form a monocyclic or polycyclic, aliphatic, aromatic or heteroaromatic ring system which may be substituted by one or more R.sup.1 radicals; Ar.sup.1 is the same or different at each instance and is an aromatic or heteroaromatic ring system which has 5 to 30 aromatic ring atoms and may be substituted by one or more nonaromatic R.sup.1 radicals; at the same time, two Ar.sup.1 radicals bonded to the same nitrogen, phosphorus, boron or silicon atom may also be bridged to one another by a single bond or a bridge selected from N(R.sup.1), C(R.sup.1).sub.2, O and S; R.sup.1 is the same or different at each instance and is selected from the group consisting of H, D, F, CN, an aliphatic hydrocarbyl radical having 1 to 20 carbon atoms, or an aromatic or heteroaromatic ring system having 5 to 30 aromatic ring atoms in which one or more hydrogen atoms may be replaced by D, F, CN or an alkyl group having 1 to 10 carbon atoms; at the same time, two or more adjacent R.sup.1 substituents together may form a mono- or polycyclic, aliphatic ring system; p is the same or different at each instance and is 0, 1, 2, 3 or 4.

2. The compound as claimed in claim 1, where in the compound is selected from the compounds of the formulae (3) to (8) ##STR00313## ##STR00314## where the symbols and indices used have the definitions given in claim 1.

3. The compound as claimed in claim 1, wherein p is the same or different at each instance and is 0 or 1.

4. The compound as claimed in claim 1, wherein the compound is selected from the compounds of the formulae (3a) to (8a) ##STR00315## ##STR00316## where the symbols used have the definitions given in claim 1.

5. The compound as claimed in claim 1, wherein the compound is selected from the compounds of the formulae (3b) to (8b) ##STR00317## ##STR00318## where the symbols used have the definitions given in claim 1.

6. The compound as claimed in claim 1, wherein A is oxygen.

7. The compound as claimed in claim 1, wherein the compound is selected from the compounds of the formulae (3d) to (8d) ##STR00319## ##STR00320## where the symbols used have the definitions given in claim 1.

8. The compound as claimed in claim 1, wherein Ar is selected from the group consisting of phenyl, biphenyl, terphenyl, quaterphenyl, fluorene, spirobifluorene, naphthalene, indole, benzofuran, benzothiophene, carbazole, dibenzofuran, dibenzothiophene, indenocarbazole, inclolocarbazole, pyridine, pyrimidine, pyrazine, pyridazine, triazine, phenanthrene, triphenylene and combinations of two or three of these groups, where these groups may each be substituted by one or more R radicals.

9. The compound as claimed in claim 1, wherein R is the same or different at each instance and is selected from the group consisting of H, D, F, CN, N(Ar.sup.1).sub.2, C(O)Ar.sup.1, P(O)(Ar.sup.1).sub.2, a straight-chain alkyl or alkoxy group having 1 to 10 carbon atoms or a branched or cyclic alkyl or alkoxy group having 3 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, each of which may be substituted by one or more R.sup.1 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by O and where one or more hydrogen atoms may be replaced by D or F, or an aromatic ring system which has 5 to 30 aromatic ring atoms and may be substituted in each case by one or more R.sup.1 radicals.

10. A process for preparing the compound as claimed in claim 1, comprising the reaction steps of: a) synthesizing the base skeleton which does not yet contain an Ar group; and b) converting the base skeleton from a) in a CN coupling or in a nucleophilic aromatic substitution reaction for introduction of the Ar group.

11. A formulation comprising at least one compound as claimed in claim 1 and at least one solvent.

12. An electronic device comprising the formulation as claimed in claim 11.

13. An electronic device comprising at least one compound as claimed in claim 1.

14. An organic electroluminescent device which comprises the compound as claimed in claim 1 is used in an emitting layer as matrix material for phosphorescent emitters or in an electron transport layer or in a hole transport layer or in an exciton blocker layer or in a hole blocker layer.

Description

(1) Examples:

(2) The syntheses which follow, unless stated otherwise, are conducted under a protective gas atmosphere in dried solvents. The solvents and reagents can be purchased from ALDRICH or ABCR. The numbers given for the reactants that are not commercially available are the corresponding CAS numbers.

(3) a) Spiro[2-bromo-9H-fluorene-9,9-(9H)-xanthene]

(4) ##STR00179##

(5) 31.7 g (127 mmol) of 1-bromo-2-diphenyl ether are dissolved in a baked-out flask in 400 mL of dried THF. The reaction mixture is cooled to 78 C. At this temperature, 55 mL of a 2.5 M solution of n-butyllithium in hexane (127 mmol) are slowly added dropwise. The mixture is stirred at 70 C. for a further 1 h. Subsequently, 30 g of 2-bromofluorenone (116 mmol) are dissolved in 100 mL of THF and added dropwise at 70 C. After the addition has ended, the reaction mixture is left to warm up gradually to room temperature, quenched with NH.sub.4Cl and then concentrated on a rotary evaporator. The concentrated solution is admixed cautiously with 300 mL of acetic acid. Subsequently, 50 mL of fuming HCl are added. The mixture is heated to 75 C. for 6 h. During this time, a white solid precipitates out. The mixture is then left to cool to room temperature, and the precipitated solid is filtered off with suction and washed with methanol. Yield: 45 g (95%)

(6) The following compounds are prepared in an analogous manner:

(7) TABLE-US-00002 Reactant 1 Reactant 2 Product Yield a1 0 77% a2 65% a3 73%
b) 2-Chlorophenyl-4-spiro-[9H-fluorene-9,9-(9H)-xanthenylamine

(8) ##STR00189##
62.6 g (137 mmol) of spiro[2-bromo-9H-fluorene-9,9-(9H)-xanthene], 17.9 g (140 mmol) of 2-chloroaniline, 68.2 g (710 mmol) of sodium tert-butoxide, 613 mg (3 mmol) of palladium(II) acetate and 3.03 g (5 mmol) of dppf are dissolved in 1.3 L of toluene and stirred under reflux for 5 h. The reaction mixture is cooled down to room temperature, extended with toluene and filtered through Celite. The filtrate is concentrated under reduced pressure and the residue is crystallized from toluene/heptane. The product is isolated as a colorless solid. Yield: 58.4 g (127 mmol), 84% of theory.

(9) The following compounds can be prepared in an analogous manner:

(10) TABLE-US-00003 Reactant 1 Reactant 2 Product Yield b1 0 80% b2 73% b3 64% b4 00 01 56% b5 02 03 04 69% b6 05 06 07 64% b7 08 09 0 60% b8 64%
c) Cyclization

(11) ##STR00214##
46.6 g (102 mmol) of (2-chlorophenyl)-4-spiro-9,9-bifluorenylamine, 56 g (409 mmol) of potassium carbonate, 4.5 g (12 mmol) of tricyclohexylphosphine tetrafluoroborate and 1.38 g (6 mmol) of palladium(II) acetate are suspended in 500 mL of dimethylacetamide and stirred under reflux for 6 h. After cooling, the reaction mixture is extended with 300 mL of water and stirred for a further 30 min, the organic phase is removed and the latter is filtered through a short Celite bed and then the solvent is removed under reduced pressure. The crude product is subjected to hot extraction with toluene and recrystallized from toluene. The product is isolated as a beige solid. Yield: 33 g (78 mmol), corresponding to 77% of theory.

(12) The following compounds can be prepared in an analogous manner:

(13) TABLE-US-00004 Reactant Product Yield c1 71% c2 78% c3 0 73% c4 70% c5 69% c6 58% c7 60% 30% c8 0 76%
d) Nucleophilic Aromatic Substitution

(14) ##STR00232##
4.2 g of 60% NaH in mineral oil (106 mmol) are dissolved in 300 mL of dimethylformamide under a protective atmosphere. 46 g (106 mmol) of indeno[1,2-a]carbazole derivative (from c) are dissolved in 250 mL of DMF and added dropwise to the reaction mixture. After 1 h at room temperature, a solution of 2-chloro-4,6-diphenyl-[1,3,5]-triazine (34.5 g, 122 mmol) in 200 mL of THF is added dropwise. The reaction mixture is stirred at room temperature for 12 h. After this time, the reaction mixture is poured onto ice. After warming to room temperature, the solids that precipitate out are filtered and washed with ethanol and heptane. The residue is subjected to hot extraction with toluene, recrystallized from toluene/n-heptane and finally sublimed under high vacuum. The purity is 99.9%. Yield of product d: 30 g (46 mmol), corresponding to 43% of theory.

(15) The following compounds can be prepared in an analogous manner:

(16) TABLE-US-00005 Reactant 1 Reactant 2 Product Yield 1d 40% 2d 39% 3d 0 44% 4d 31% 5d 43% 6d 0 41% 7d 39% 8d 46% 9d 40% 10d 0 51%
e) Buchwald Reaction

(17) ##STR00263##
44.6 g (106 mmol) of indeno[1,2-a]carbazole derivative (from c), 17.9 g (114 mmol) of bromobenzene and 30.5 g of NaOtBu are suspended in 1.5 L of p-xylene. To this suspension are added 0.5 g (2.11 mmol) of Pd(OAc).sub.2 and 1.6 mL of a 1M tri-tert-butylphosphine solution. The reaction mixture is heated under reflux for 16 h. After cooling, the organic phase is removed, washed three times with 200 mL of water and then concentrated to dryness. The residue is subjected to hot extraction with toluene, recrystallized from toluene and finally sublimed under high vacuum. The purity is 99.9% with a yield of product e of 22.6 g (45 mmol; 43%).

(18) The following compounds can be prepared in an analogous manner:

(19) TABLE-US-00006 Reactant 1 Reactant 2 Product Yield 1e 39% 2e 41% 3e 0 42% 4e 34% 5e 45% 6e 0 42% 7e 40% 8e 47%

(20) Example: Production of the OLEDs

(21) In examples C1 to I11 which follow (see tables 1 and 2), the data of various OLEDs are presented. Cleaned glass plaques (cleaning in laboratory glass washer, Merck Extran detergent) coated with structured ITO (indium tin oxide) of thickness 50 nm are pretreated with UV ozone for 25 min (PR-100 UV ozone generator from UVP) and, for improved processing, coated with 20 nm of PEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), purchased as CLEVIOS P VP Al 4083 from Heraeus Precious Metals GmbH Deutschland, spun on from aqueous solution) and then baked at 180 C. for 10 min. These coated glass plaques form the substrates to which the OLEDs are applied.

(22) The OLEDs basically have the following layer structure: substrate/hole transport layer (HTL)/optional interlayer (IL)/electron blocker layer (EBL)/emission layer (EML)/optional hole blocker layer (HBL)/electron transport layer (ETL)/optional electron injection layer (EIL) and finally a cathode. The cathode is formed by an aluminum layer of thickness 100 nm. The exact structure of the OLEDs can be found in table 1. A reference such as e or 6e in table 1 relates to the corresponding materials shown in table 3. The further materials required for production of the OLEDs are shown in table 3.

(23) All materials are applied by thermal vapor deposition in a vacuum chamber. In this case, the emission layer always consists of at least one matrix material (host material) and an emitting dopant (emitter) which is added to the matrix material(s) in a particular proportion by volume by co-evaporation. Details given in such a form as IC2:6e:TEG1 (40%:50%:10%) mean here that the material IC2 is present in the layer in a proportion by volume of 40%, 6e in a proportion of 40% and TEG1 in a proportion of 10%. Analogously, the electron transport layer may also consist of a mixture of two materials.

(24) The OLEDs are characterized in a standard manner. For this purpose, the electroluminescence spectra, the current efficiency (measured in cd/A), the power efficiency (measured in Im/W) and the external quantum efficiency (EQE, measured in percent) are determined as a function of luminance, calculated from current-voltage-luminance characteristics (IUL characteristics) assuming Lambertian radiation characteristics. The electroluminescence spectra are determined at a luminance of 1000 cd/m.sup.2, and the CIE 1931 x and y color coordinates are calculated therefrom. The parameter U1000 in Table 2 refers to the voltage which is required for a luminance of 1000 cd/m.sup.2. CE1000 and PE1000 respectively refer to the current and power efficiencies which are achieved at 1000 cd/m.sup.2. Finally, EQE1000 refers to the external quantum efficiency at an operating luminance of 1000 cd/m.sup.2.

(25) The data for the various OLEDs are collated in Table 2. Examples C1-C5 are comparative examples according to the prior art; examples I1-I11 show data of OLEDs comprising inventive materials.

(26) Some of the examples are elucidated in detail hereinafter, in order to illustrate the advantages of the compounds of the invention.

(27) Use of Compounds of the Invention as Electron Transport Materials

(28) Through the use of compounds of the invention in the electron transport layer of OLEDs, it is possible to achieve distinct increases in terms of operating voltage, external quantum efficiency and hence in particular power efficiency as well. In this regard, see examples C1, C2 and I1-I3.

(29) Use of Compounds of the Invention as Matrix Materials in Phosphorescent OLEDs

(30) The materials of the invention, when used as matrix materials in phosphorescent OLEDs, give significant improvements compared to the prior art. With the compounds 6d, 1d, 8e, for example, much lower operating voltage and higher efficiency are obtained than with the compounds PA1 and PA2. In this regard, see examples C3, C4 and I9-I11.

(31) In addition, compounds of the invention can achieve improvements in the case of mixing with a second matrix material. Compared to the compound PA3 which, in combination with IC2, already gives very good performance data, an improvement is obtained through the use of the compounds e and 6e. In this regard, see examples C5, I5 and I6.

(32) TABLE-US-00007 TABLE 1 Structure of the OLEDs HTL IL EBL EML HBL ETL EIL Ex. thickness thickness thickness thickness thickness thickness thickness C1 SpA1 HATCN SpMA1 IC1:TEG1 PA1 LiQ 70 nm 5 nm 90 nm (90%:10%) 30 nm 40 nm 4 nm C2 SpA1 HATCN SpMA1 IC1:TEG1 PA2 LiQ 70 nm 5 nm 90 nm (90%:10%) 30 nm 40 nm 4 nm C3 SpA1 HATCN SpMA1 PA1:TEG1 (90%:10%) ST2:LiQ 70 nm 5 nm 90 nm 30 nm (50%:50%) 40 nm C4 SpA1 HATCN SpMA1 PA2:TEG1 (90%:10%) IC1 ST2:LiQ 70 nm 5 nm 90 nm 30 nm 10 nm (50%:50%) 30 nm C5 SpA1 HATCN SpMA1 IC2:PA3:TEG1 IC1 ST2:LiQ 70 nm 5 nm 90 nm (40%:50%:10%) 30 nm 10 nm (50%:50%) 30 nm I1 SpA1 HATCN SpMA1 IC1:TEG1 d LiQ 70 nm 5 nm 90 nm (90%:10%) 30 nm 40 nm 4 nm I2 SpA1 HATCN SpMA1 IC1:TEG1 9d LiQ 70 nm 5 nm 90 nm (90%:10%) 30 nm 40 nm 4 nm I3 SpA1 HATCN SpMA1 IC1:TEG1 8e LiQ 70 nm 5 nm 90 nm (90%:10%) 30 nm 40 nm 4 nm I4 SpA1 HATCN SpMA1 d:TER1 ST2:LiQ 90 nm 5 nm 130 nm (92%:8%) 40 nm (50%:50%) 40 nm I5 SpA1 HATCN SpMA1 IC2:e:TEG1 IC1 ST2:LiQ 70 nm 5 nm 90 nm (40%:50%:10%) 30 nm 10 nm (50%:50%) 30 nm I6 SpA1 HATCN SpMA1 IC2:6e:TEG1 IC1 ST2:LiQ 70 nm 5 nm 90 nm (40%:50%:10%) 30 nm 10 nm (50%:50%) 30 nm I7 SpA1 HATCN SpMA1:5e IC1:TEG1 IC1 ST2:LiQ 70 nm 5 nm (85%:15%) (90%:10%) 30 nm 10 nm (50%:50%) 30 nm 90 nm I8 SpA1 HATCN SpMA1 10d:BIC1:TEG1 IC1 ST2:LiQ 70 nm 5 nm 90 nm (55%:40%:5%) 30 nm 10 nm (50%:50%) 30 nm I9 SpA1 HATCN SpMA1 6d:TEG1 (90%:10%) ST2:LiQ 70 nm 5 nm 90 nm 30 nm (50%:50%) 40 nm I10 SpA1 HATCN SpMA1 1d:TEG1 (90%:10%) ST2:LiQ 70 nm 5 nm 90 nm 30 nm (50%:50%) 40 nm I11 SpA1 HATCN SpMA1 8e:TEG1 (90%:10%) IC1 ST2:LiQ 70 nm 5 nm 90 nm 30 nm 10 nm (50%:50%) 30 nm

(33) TABLE-US-00008 TABLE 2 Data of the OLEDs U1000 CE1000 PE1000 EQE CIE x/y at Ex. (V) (cd/A) (lm/W) 1000 1000 cd/m.sup.2 C1 3.6 51 45 14.5% 0.34/0.62 C2 3.8 54 44 15.2% 0.33/0.62 C3 3.5 51 46 14.3% 0.33/0.62 C4 3.7 56 48 15.7% 0.33/0.62 C5 3.3 59 55 16.2% 0.33/0.62 I1 3.0 58 61 16.3% 0.34/0.62 I2 3.4 56 52 15.6% 0.33/0.63 I3 3.2 60 59 17.0% 0.33/0.62 I4 4.1 12.1 9.4 13.1% 0.67/0.33 I5 3.2 61 59 17.2% 0.34/0.61 I6 3.3 65 63 18.2% 0.34/0.62 I7 3.6 59 52 16.7% 0.34/0.62 I8 3.3 60 57 16.6% 0.33/0.62 I9 3.4 67 61 18.6% 0.33/0.62 I10 3.2 61 60 17.1% 0.34/0.62 I11 3.2 59 57 16.5% 0.33/0.62

(34) TABLE-US-00009 TABLE 2 Structural formulae of the materials for the OLEDs HATCN SpA1 0 LiQ TEG1 IC1 ST2 SpMA1 TER1 IC2 BIC1 d 1d 00 6d 01 9d 02 10d 03 8e 04 e 05 5e 06 6e 07 PA1 08 PA2 09 PA3